The U.S. military is investing in new storage technology because most of the weight that soldiers carry on their backs is batteries. Once that gets developed for the military, it will be expanded to civilians.

When you have a vision of where you need to go, it sounds utopian. But when you get to the tipping point, your understanding switches.

The fact that solar has gone down 80 percent since 2008 is astonishing. Wind is perhaps not coming down as quickly. Lack of storage - batteries - is a bottleneck. That makes it very difficult to put large amounts of renewable energy on the grid.

The fact is, when you talk to people, they know that something weird is going on, particularly people who are connected to the land or the water. They can see it. What perhaps is not so evident to them, unfortunately, is what the solution is. But whether they call it climate change or not, it doesn't matter. The point is, they can see there's something fundamentally weird going on here.

The record-breaking extreme weather events causing chaos across the globe should be a wake-up call. The transition to a low-carbon economy will be much more painful if we wait until there is a climate crisis before recognising that more than half of the world's fossil fuel reserves will have to remain in the ground.

Each building should produce as least as much energy as it's going to need, and have more to put on the grid. They should be using all of the natural light and natural heat.

We will move to a low-carbon world because nature will force us, or because policy will guide us. If we wait until nature forces us, the cost will be astronomical.